diff --git a/drivers/i2c/i2c-mux.c b/drivers/i2c/i2c-mux.c
index 603252fa1284..8d5e4c6fdd8e 100644
--- a/drivers/i2c/i2c-mux.c
+++ b/drivers/i2c/i2c-mux.c
@@ -243,8 +243,7 @@ struct i2c_mux_core *i2c_mux_alloc(struct i2c_adapter *parent,
 {
 	struct i2c_mux_core *muxc;
 
-	muxc = devm_kzalloc(dev, sizeof(*muxc)
-			    + max_adapters * sizeof(muxc->adapter[0])
+	muxc = devm_kzalloc(dev, struct_size(muxc, adapter, max_adapters)
 			    + sizeof_priv, GFP_KERNEL);
 	if (!muxc)
 		return NULL;